Alarm devices are used for securing articles against unauthorised theft. For example, it is known to equip bicycle locks with an alarm device, in which case the alarm device can be carried by a user, in other words can basically be considered portable, and usually comprises a steel cable which can be fastened to the bicycle and if appropriate to an article in the vicinity. One end of a steel cable of this type is rigidly connected to the alarm emitter, whilst the other end is open, and can thus for example be guided through bicycle spokes or through the frame so as subsequently to connect this end to the alarm emitter, which thus also simultaneously has a locking function.
The primary function is to prevent theft of the secured article, such as in this case a bicycle, although embodiments are also known in the art in which the cutting of the steel cable is detected and hereafter an alarm, in particular an acoustic alarm, is triggered. To make detection of this type possible, it is known to form an electrical circuit using the steel cable mentioned at the outset, the opening of said circuit when the steel cable is cut being detected by the alarm emitter.
Alarm devices of this type are destroyed as a result of the steel cable which is formed as a sensor element being cut, in other words cannot be reused in future.
Further, alarm devices of this type, comprising sensor elements which are also intended to make theft difficult or impossible, have the drawback of a very high weight, and so, although alarm devices of this type are portable in principle, they cannot be carried comfortably by a user.
Further, a further drawback of alarm devices of this type is that they are tailored to a specific application, such as in this case making bicycle theft more difficult and providing an acoustic indication of bicycle theft, and therefore known alarm devices of this type generally cannot be used universally.